Initializing a DNS Resolver with Priming Queries
draft-ietf-dnsop-resolver-priming-06

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Document Type Active Internet-Draft (dnsop WG)
Last updated 2016-01-13
Replaces draft-koch-dnsop-resolver-priming
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Intended RFC status Best Current Practice
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Network Working Group                                            P. Koch
Internet-Draft                                                  DENIC eG
Intended status: Best Current Practice                         M. Larson
Expires: July 16, 2016                                         Dyn, Inc.
                                                              P. Hoffman
                                                                   ICANN
                                                        January 13, 2016

            Initializing a DNS Resolver with Priming Queries
                  draft-ietf-dnsop-resolver-priming-06

Abstract

   This document describes the queries a DNS resolver can emit to
   initialize its cache.  The result is that the resolver gets both a
   current NS RRSet for the root zone and the necessary address
   information for reaching the root servers.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on July 16, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   Recursive DNS resolvers need a starting point to resolve queries.
   [RFC1034] describes a common scenario for recursive resolvers: they
   begin with an empty cache and some configuration for finding the
   names and addresses of the DNS root servers.  [RFC1034] describes
   that configuration as a list of servers that will authoritative
   answers to queries about the root.  This has become a common
   implementation choice for recursive resolvers, and is the topic of
   this document.

   This document describes the steps needed for this common
   implementation choice.  Note that this is not the only way to start a
   recursive name server with an empty cache, but it is the only one
   described in [RFC1034].  Some implementers have chosen other
   directions, some of which work well and others of which fail
   (sometimes disastrously) under different conditions.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   This document only deals with recursive name servers (recursive
   resolvers, resolvers) for the IN class.

2.  Description of Priming

   As described in this document, priming is the act of finding the list
   of root servers from a configuration that lists some or all of the
   purported IP addresses of some or all of those root servers.  A
   recursive resolver starts with no information about the root servers,
   and ends up with a list of their names and their addresses.

   Priming is described in Sections 5.3.2 and 5.3.3 of [RFC1034].  The
   scenario used in that description, that of a recursive server that is
   also authoritative, is no longer as common.

   Currently, it is quite common for the configured list of IP addresses
   for the root server to be mostly complete and correct.  Note that
   this list (at least initially) comes from the vendor or distributor
   of the recursive server software.

   The list of root server operators and the domain name associated with
   each one has been stable since 1997.  However, there are address
   changes for the NS records for those root server operators, both for

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   IPv4 and IPv6 addresses.  However, research shows that after those
   addresses change, some resolvers never get the new addresses.
   Therefore, it is important that resolvers be able to cope with
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